Method of dredging



1,636,205. July! 1927' N. A. YUlLLE I METHOD OF DREDGING Filed A ril 12.1926

plfilcrmuarswmanvd NATHAN/EL. A Yu/LLE MA fjww ntoz 5 lit Patented July 19,1927.

UNITED STATES PATENT OFFICE,

i METHOD OF DREDGING.

Application filed April 12, 1926. Serial N0. 101,231.

This invention relates to suction dredging wherein a revolving cutter lowered from a dredge cuts up the mud under the water and the loosened material is drawn through a suction pipe for ejection at some remote point.

The object of the invention is to provide an improved method of operating the revolving cutters of such dredges as well as an improved form of cutter better adapted to be so operated.

In the drawings hereto my invention is shown, though since it refers to a method rather than to precise mechanical details the drawings are not filled with the details of suction dredge construction as such forms no part of the invention and is well understood by those familiar with the art.

Figure 1 of the drawing is a plan view oi a suction dredge operating in a river and indicates the swinging of the dredge in cut ting a curved swath through the mud.

Figure 2 is an enlarged diagrammatic representation of the action of the cutter against the mud under opposite directions of travel with constant; direction of rotation.

Figure 3 is an enlarged end view of a cutter showing the usual form of blades, while Figure 4: a similar view showing a form of blade better adapted for carrying out my improved method of operation.

In theconnnon method of suction dredging, a dredge 1 operating in a waterway 2 is alternately swung back and forth on spuds 3 and 3' so as to advance in steps along the waterway and swing the cutter 4 at the lower end of the ladder 5 in curved paths 6 in the mud "for withdrawal of same through the suction pipe 7 in the well known way.

The cutter 4 may be made with various jaws or blades but consists essentially of revolving blades so shaped as to cut the mud and draw it into the cutter for delivery to the open end of the suction pipe there located' Some of the cutters have the cutting edges at. the periphery of the device ladder and to the upper end of which shaft power is applied, usually through an engine or other prime mover located on the upper end of the ladder as at 10.

Since the cutter always rotates in one direction as prescribed. by the angular proection of the cutter blades it gives rise to an unsatisfactory cutting action in one direction of the swing of the dredge.

This is shown in Figure 2 and is due to the fact that when the dredge is swinging in direction A the cutter is revolving under or 111 opposition to a bank B of mud while when swinging in the opposite direction 0 upon return it is revolving against the top of the bank D.

This latter condition produces a tendency for the cutter to walk or ride over the mud like a rolling wheel thereby greatly reducing the eficiency of the device at the return swing, and resulting in ridges of mud being left upon the return swing instead of an even depth of cut with the opposite swings of the cutter.

To overcome this faulty condition I propose to provide a cutter which will cutequally well when rotated in either direction, and with such a cutter mounted on the usual suction dredge to reverse the direction of rotation of the cutter with the alternative swinging paths of travel so that the cutter will always work under the mud bank as indicated at B in Figure 2.

' hether the driving engine is alternately reversed, or gears are changed to accomplish this is immaterial, as this would depend on the particular driving equipment used, and it also is within the purview of the invention to effect a reversible cutter by providing reversible bladesas well understood in ship propellers or in forming fixed blades 12 as shown in the cutter 4 of Fig. 4 and which are oppositely hooked at the cutting edges 13 so as to cut and draw the mud inwardly in either direction of travel so that it will enter the opening 7' of the suction pipe.

I claim:

A rotary cutter for a suction dredge provided with fixed arms each bifurcated at its end to form a pair of sharp cutting blades, said blades being hooked and arched, one in the direction of rotation and the other in reverse direction of rotation of the cutter and the tips of theblades all terminating on acommon circle.

NATHANIEL A. YUILLE. 

